Fractionalized stimulation pulses in an implantable stimulator device

Abstract

A method for configuring stimulation pulses in an implantable stimulator device having a plurality of electrodes is disclosed, which method is particularly useful in adjusting the electrodes by current steering during initialization of the device. In one aspect, a set of ideal pulses for patient therapy is determined, in which at least two of the ideal pulses are of the same polarity and are intended to be simultaneous applied to corresponding electrodes on the implantable stimulator device during an initial duration. These pulses are reconstructed into fractionalized pulses, each comprised of pulse portions. The fractionalized pulses are applied to the corresponding electrodes on the device during a final duration, but the pulse portions of the fractionalized pulses are not simultaneously applied during the final duration.

What is claimed is: 
     
       1. An implantable medical device, comprising:
 source circuitry configured to convert first stimulation parameters into a current that is sourced to a first electrode; 
 sink circuitry configured to convert second stimulation parameters into a current that is sunk from a second electrode; 
 control logic configured to provide the first and second stimulation parameters to the source and sink circuitry, wherein the first and second stimulation parameters define a group of a plurality of pulses, and wherein the plurality of pulses have a first frequency of greater than or equal to 2,000 Hz within the group, 
 wherein the first and second stimulation parameters define a periodic application of the group at a second frequency that results in a time between consecutive applications of the group during which the pulses are not active. 
 
     
     
       2. The implantable medical device of  claim 1 , further comprising a receiver configured to wirelessly receive the first and second stimulation parameters from a device external to the implantable medical device. 
     
     
       3. The implantable medical device of  claim 2 , further comprising a memory to store the received first and second stimulation parameters. 
     
     
       4. The implantable medical device of  claim 2 , wherein the first and second stimulation parameters define a duration of the group. 
     
     
       5. The implantable medical device of  claim 4 , wherein the duration is determined to be therapeutically effective at the external device. 
     
     
       6. The implantable medical device of  claim 2 , wherein the first and second stimulation parameters define a periodic application of the group at a second frequency. 
     
     
       7. The implantable medical device of  claim 6 , wherein the second frequency is determined to be therapeutically effective at the external device. 
     
     
       8. The implantable medical device of  claim 1 , wherein the pulses within the group have a duty cycle. 
     
     
       9. The implantable medical device of  claim 8 , wherein the duty cycle is approximately 50%. 
     
     
       10. The implantable medical device of  claim 1 , wherein the first frequency is less than or equal to 10,000 Hz. 
     
     
       11. The implantable medical device of  claim 1 , wherein the source circuitry and the sink circuitry comprise constant current circuitry. 
     
     
       12. The implantable medical device of  claim 1 , further comprising first and second leads coupled to the implantable medical device, wherein each of the first and second electrodes is carried on one of the first and second leads. 
     
     
       13. The implantable medical device of  claim 12 , wherein the first and second leads are implanted on either side of a physiological midline of a patient's spinal cord. 
     
     
       14. The implantable medical device of  claim 12 , wherein the first and second leads are positioned within an epidural space of a patient's spinal cord. 
     
     
       15. The implantable medical device of  claim 1 , wherein the first stimulation parameters define the group and wherein the second stimulation parameters define a non-pulsed, constant-amplitude current that is simultaneous with the group. 
     
     
       16. The implantable medical device of  claim 15 , wherein the current that is sourced to the first electrode and the current that is sunk from the second electrode are equivalent in electrical charge. 
     
     
       17. An implantable medical device, comprising:
 source circuitry configured to convert first stimulation parameters into a current that is sourced to a first electrode; 
 sink circuitry configured to convert second stimulation parameters into a current that is sunk from a second electrode; 
 control logic configured to provide the first and second stimulation parameters to the source and sink circuitry, wherein the first and second stimulation parameters define a group of a plurality of pulses, and wherein the plurality of pulses have a first frequency of greater than or equal to 2,000 Hz within the group, 
 wherein the first and second stimulation parameters define the group within a single timing channel. 
 
     
     
       18. An implantable medical device, comprising:
 source circuitry configured to convert first stimulation parameters into a current that is sourced to a first electrode; 
 sink circuitry configured to convert second stimulation parameters into a current that is sunk from a second electrode; 
 control logic configured to provide the first and second stimulation parameters to the source and sink circuitry, wherein the first and second stimulation parameters define a group of a plurality of pulses, and wherein the plurality of pulses have a first frequency of greater than or equal to 2,000 Hz within the group, 
 wherein the plurality of pulses in the group are either only anodic or only cathodic.